1. Field of the Invention
The present invention relates to systems and methods for treating biological vessels and more particularly reshaping veins and to modify their biomechanics in order to allow a reduction in blood flow either permanently or in response to an increase in surrounding blood pressure. In particular, the present invention relates to devices and methods for treating erectile dysfunction and, more particularly, to devices for reshaping the lumen of a penile vein to reduce flow therethrough during penile tumescence.
Venous leaks include various phenomenon where changes in or around the venous system cause a noticeable clinical impact. For example, the veins have internal valves that prevent back flow and allow blood flow back to the heart in the low pressure venous system. Vascular leaks may occur as a vein diameter increases around which can inhibit valve closure (causing a venous leak). Such venous leaks may cause an accumulation of blood in the lower extremities that in turn may cause discomfort and pain. It is desirable to be able to reshape the vein with the goal of restoring the functionality of the valve.
Venous valves also play an important role in penile erection. Penile erection results from increased local blood pressure in the penis. Two corpora cavernosa located in the penis fill with blood coming from the deep arteries of the penis. Expansion of the corpora cavernosa compresses the associated outflow veins, thus inhibiting the blood outflow and allowing the increased local blood pressure to cause an erection.
In a large percentage of men over age 40, this functionality is impaired, commonly referred to as erectile dysfunction (ED). While the cause can be an insufficient inflow of blood (arteriogenic ED) in many cases the cause is the incomplete inhibition of venous outflow (venogenic ED). Incomplete venous occlusion typically results from changes in the biomechanical behavior of the veins that increase resistance to pressure.
Presently, ED has limited treatment options. Available medications typically increase blood inflow and may not be effective in men suffering from venous leak. Other treatment options usually involve a major surgery and complete occlusion of major vein, but such treatment suffers from poor long term outcomes. The failure of complete venous occlusion is believed to be caused by the development of collateral veins in response to complete occlusion of the deep dorsal vein and/or other penile veins.
As an alternative to surgery, various external compression devices have been proposed to treat ED by inhibiting blood outflow. Most such devices, however, user actuation and are uncomfortable to wear and use.
For these reasons, it would be desirable to provide procedures and devices with improved short term and/or long term results for treating ED and modulating flow through other veins. It would further be desirable to provide devices for inhibiting venous flow which may be implanted in relatively simple procedure, particularly outpatient procedures and procedures that can be performed in a doctor's office with local or no anesthesia. In particular, such devices and methods should be simple and effective for treating ED. At least some of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Methods and devices for treating ED and for modulating blood flow through veins and arteries are described in US Patent Publs. 2005/0277907; 2011/0066254; and 2011/007458; and U.S. Pat. No. 8,240,313. See also Rao and Donatucci (2001) Urologic Clinics 28:309-319. Devices for applying external vein compression are described in US2009/0248109 and US2011/0087337.